- Spain’s energy and competition watchdog, the CNMC, said it found long‑term breaches of electricity system rules that may have affected power‑system operations, prompting it to open formal investigations.
- On April 28, 2025, a sudden voltage surge caused a major blackout across Spain and Portugal. The CNMC said the suspected breaches did not cause the outage but may have contributed to system instability.
- Proceedings can last nine to eighteen months, during which the regulator will examine evidence and allow parties to present arguments.
Spain’s National Commission on Markets and Competition has launched formal investigations into the causes of the unprecedented blackout that plunged large parts of Spain and Portugal into darkness on 28 April 2025. The watchdog said it had found evidence that certain power sector rules were breached over extended periods, potentially undermining grid stability.
The regulator emphasised that while these rule violations did not directly cause the blackout, they may have affected how the power system responded to the voltage surge that triggered the outage. Investigators will now examine whether the breaches amounted to administrative violations and whether penalties or reforms are necessary.
The CNMC said the chain of events leading to the blackout progressively destabilised the power grid, culminating in a massive outage.
In a separate report released last month, the CNMC recommended a suite of measures to improve grid resilience. These include mitigating voltage swings through advanced control systems and enhancing cross‑border interconnections with France to spread risk. Such measures would allow operators to draw on neighbouring systems during disturbances.
The formal investigation could take between nine and eighteen months. During this period, utilities and grid operators will be given the opportunity to present evidence and argue their case. Depending on the findings, the CNMC could impose fines, mandate operational changes or propose amendments to Spain’s electricity regulations.
The probe underscores the importance of robust grid management and regulatory oversight amid the rapid integration of renewables. As more variable generation enters the system, voltage control and cross‑border cooperation become critical.
Lessons from the Iberian blackout may inform UK planning for distributed energy resources, grid upgrades and the role of regional interconnectors in enhancing resilience.
